School of Mechanical, Materials and Mechatronic Engineering
WORKSHOP Introduction to Rietveld Refinement Method for Quantitative Analysis by XRD
PRESENTER Dr Yu Wang WHERE Building 20.2 DATE Monday 6 June 2016 TIME 10:00-11:30 am
ABSTRACT Along with obtaining the updated PDF XRD database and installation of HighScore Plus software in the MMM School XRD Laboratory, students and academics are now able to utilize the XRD data for quantitative analysis of the phase composition in their samples. The aim of the workshop is to provide some basic knowledge on what can be achieved by the method which will allow XRD users to assess their demand and whether they would like to take further training on the skills in quantitative analysis using the method and software to obtain reliable results.
Quantitative X-ray diffraction analysis is commonly defined as determination of quantities of different phases in multi-phase powder sample. In this field many methods have been developed since 1930's. However the development and application were going slow because of some fundamental difficulties. Recently Rietveld refinement becomes a dominant method because its advantages are significantly over conventional quantitative methods.
Rietveld refinement, developed by Hugo Rietveld (1967), is the first of whole pattern analysis method, which puts entirely measured X-ray diffraction pattern as a target, and simulates this pattern with a computer crystal model; eventually gets a match between the measured and simulated patterns. Initially Rietveld used this method to virtually separate the overlapping diffraction peaks, and thereby accurately determined a crystal structure. Furthermore the method has been quickly adopted to quantify crystal phases. It appears standard-less (standard sample is not necessary), flexible, stable result with reasonable accuracy, particularly to a multi-phase system.
This seminar introduces the background and theory of Rietveld refinement, how does it work and why it can overcome the difficulties of the conventional method. There are a few application cases to show the strength of this method. Apart from phase quantity, Rietveld refinement has been widely used for other characterization of crystal materials, such as lattice parameters, nano-particle size, particle shape and amorphous content.
Unavoidably Rietveld refinement has its limits, but after careful XRD measurement and proper use of the program, Rietveld refinement would be a very useful tool for all scientific researches.
ABOUT THE SPEAKER Dr Yu Wang is an XRD specialist who has 20 year experience in the utilization and maintenance of XRD instruments. Currently Dr Yu Wang is managing 8 XRD instruments at UNSW and providing regular training on the use of XRD for analysis of different types of samples. At UNSW, Dr Yu Wang provides a special training of 4 days on the application of Rietveld method and HighScore Plus for quantitative analysis by XRD to UNSW XRD users, which will be make available to UOW XRD users. ?
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